NO148370B - PROCEDURE FOR PHASE PREPARATION OF OLEFINES, DIOLEFINES OR AROMATES FROM MIXTURES USING N-METHYL-MORPHOLIN-3-ON - Google Patents

Description

The present invention relates to a method by

separation of olefins, diolefins or aromatic hydrocarbons from mixtures by extraction or extractive distillation using a keto group-containing morpholine-

derivative, and the peculiarity of the invention is that N-methyl-morpholin-3-one is used as such solvent, optionally in a mixture with up to 20% by weight of water and/or other organic solvents.

These features of the invention appear in the patent claim.

The possibility of using heterocyclic compounds as extractive solvents in the separation of hydrocarbons from hydrocarbon mixtures by extractive distillation, gas-liquid scrubbing or liquid-liquid scrubbing is known.

When such connections are judged with respect to a

industrial utilization, many considerations must be taken into account, including selectivity, entrainment, stability, easy synthesis, toxicity, vapor pressure, specific weight, boiling point temperature, melting point temperature, price, commercial availability in the necessary quantities, etc.

It has now been found, and this is the purpose of the present

lying invention, that N-methyl-morpholin-3-one is a compound that satisfactorily fulfills almost all of these requirements and can thus be advantageously used as an extractive solvent when separating specified types of hydrocarbons from mixtures of these either among themselves or from mixtures with other hydrocarbons.

Use of morpholine derivatives which may individually be substituted with an oxygen-containing substituent in one or more positions in the ring, and also use of a derivative with the keto group in the side chain, namely N-acetonyl-morpholine,

as a solvent for the purpose in question, is previously known, see British patent document 1,283,519. Furthermore, it is known from BRD official publication 1,916,255 to use morpholine derivatives with oxygen-containing substituents both with and without carbon atoms, for analogous purposes. For the evaluation of the various morpholine derivatives for the aforementioned purpose, it was surprisingly found that N-methyl-morpholin-3-one,

in addition to the above-mentioned advantageous combination of properties when separating olefinic hydrocarbons, diolefins or aromatic hydrocarbons from mixtures of hydrocarbons containing them, by extraction or extractive distillation, exhibits approximately the same selectivity as previously used morpholine derivatives, but that its extractability is approximately 30% larger.

As an addition to N-methyl-morpholin-3-one can be used

e.g. ethylene glycol in an amount of up to 20% by weight.

The method is used in particular for the separation of di-olefin hydrocarbons from mixtures containing them, more particularly of butadiene from a mixture of C 1 -hydrocarbons, or of isoprene from a mixture of -hydrocarbons.

The method is advantageously also used for separation

of mixtures of saturated, olefinic or aromatic hydrocarbons from mixtures containing them, or also for the separation of an individual olefinic resp. aromatic hydrocarbon from mixtures of olefins, saturated hydrocarbons, and diolefins or from mixtures of aromatic hydrocarbons.

More particularly, mention is made of the possibility of separating styrene, benzene, toluene and xylenes, either alone or in admixture with each other, from mixtures containing them.

In the following, some examples of exemplary and preferred embodiments of the invention are given.

EXAMPLE 1

With reference to the form in fig. 1, the extractive still column 9 is fed with a stream composed of (line 1):

The working conditions are as follows:

The same column is fed through the line 2,500 kg/hour of

a mixture consisting of N-methyl-morpholin-3-one/water in the weight ratio 94 to 6.

From the top (wire 3) a current is taken out which is composed

of:

The flow coming from the bottom of the column 9 (line 4) is sent to the second extractive distillation column 10, together with a flow of 60 kg/h (line 5) of the above-mentioned solvent.

The column 10 is operated under the following conditions;

From the top (line 6) a stream of high purity isoprene is taken out, which is composed of;

In a side stream, the more polar hydrocarbons (1,3-cyclopentadiene and isopropenyl-acetylene) are taken out in the vapor phase (line 7), and from the bottom (line 8) the solvent is taken out, which is free of hydrocarbons and thus suitable for being recycled in the extractive distillation columns 9 and 10 mentioned above

EXAMPLE 2.

With reference to the form in fig. 1, the extractive distillation column 9 is supplied with 1 kg/hour of a stream composed of (line 1):

To the same column, through line 2, 10 kg/hour is sent

of a mixture consisting of N-methyl-1-morpholin-3-one and water in the weight ratio 93/7.

A current of 0.65 kg/hour is taken from the top (line 3).

which mainly contain saturated and olefinic hydrocarbons.

The current coming from the bottom of column 9 (wire 4)

is sent to the second extraction column 10 together with a flow of 2 kg/hour (line 5) of the above solvent.

The separation in column 10 is carried out under the following conditions:

From the top, a current of approx

0.34 kg/hour of 1,3-butadiene with a high degree of purity and containing about 20 ppm (parts per million) of acetylene compounds.

From a side stream in the vapor phase (line 7) the acetylene hydrocarbons are taken out together with a very small amount of butadiene, while from the bottom (line 8) the hydrocarbon-free solvent is taken out, and which is suitable for renewed use in the extraction columns 9 and 10 as previously mentioned .

EXAMPLE 3.

With reference to the form according to fig. 2, the extractive distillation column 8 is supplied with a reformed gasoline flow (line 1) composed of:

The working conditions are as follows:

The same column is fed through line 2 30 kg/hour of

a mixture of N-methyl-morpholin-3-one and monoethylene glycol in the weight ratio 95/5.

A current of 3.05 kg/hour is taken from the top (line 3).

containing essentially all the non-aromatic hydrocarbons added to the same column 8„

The bottom product is sent again through line 4 to a stripping column (9) which is operated under the following conditions):

From the top (line 5) a stream of aromatic hydrocarbons with a predetermined amount of saturated compounds is obtained while the solvent is recovered from the bottom, as this is necessary for the operation of the column 8.

The stripping of the flow taken out from the bottom of the column 8 can

is also carried out in two stages, as indicated in the form according to fig. 3.

In such a case, the same bottom product (line 4) is sent

to a first stripping column (9) which is operated under the following conditions:

From the top (line 5) a stream is obtained with a specified content of saturated compounds composed of:

From the bottom (line 6) a current is taken out and sent to another stripping column (10) which is operated under the following conditions:

While a stream of xylenes is withdrawn from the top (line 7) according to predetermined specifications (3.03 kg/hour), the solvent is recovered from the bottom, as this is necessary for the operation of the column (8).

EXAMPLE 4.

With reference to the form according to fig. 4, the extractive distillation column (9) is supplied with a flow (line 1) of 100 kg/hour of a Cg fraction with the following composition;

The working conditions are as follows:

The same column is supplied through line 2 with 1,300 kg/hour of a mixture consisting of N-methyl-morpholin-3-one and water in the weight ratio 96/4.

From the top (line 3), water and a stream of organically refined mixture consisting of:

This stream is sent to a phase separator (11) to separate water (17) from the refined mixture (16).

The bottom fraction is taken out in a stream (line 4) which is sent to the extraction column (10) together with a stream of 150 kg/hour of the above-mentioned solvent. The separation in the last column is carried out under the following conditions:

A stream consisting of o-xylene and styrene is withdrawn from the top (line 6) and recycled to the column (9), while a stream (7) is withdrawn from the bottom and fed to the stripping column (12).

This stripping column is operated under the following conditions:

From the top, a stream is taken which is sent to the phase separator (13. From line 8, styrene is obtained with a purity of more than 99.8%.

From the top of the same column, the solvent is removed which, after mixing in 15 with hot water from 17 and 18, is recycled.

EXAMPLE 5.

With reference to the form according to Fig. 5, a flow of 1 kg/hour composed of:

The same column is supplied through line 2 with approximately 8.5 kg/hour of a mixture consisting of N-methyl-morpholin-3-one and water in the weight ratio 94/6.

From the top (line 3) a gas stream of 0.65 kg/hour is taken out, which mainly contains saturated and olefinic hydrocarbons, while the bottom stream (line 4) is sent to the stripping column (10).

The operation of the last column is characterized by:

A gas stream of C4 olefins and 1,3-butadiene is taken out from the top (line 5), which is recycled to the column (9), while it is taken out from the bottom. a stream (6) which is supplied to the second stripping column (11). The last column is operated under the following conditions:

The gas stream that is taken out from the top is sent to the compressor (12).

After condensation, approx

0.35 kg/hour of 1,3-butadiene which, according to further specifications, contains saturated and olefinic compounds (purity more than 99.5% by weight) while through the line (7) fractions of the above stream are taken out and recycled to the column (10).

Solvent is recovered from the bottom of (11) and recycled in column (9).

EXAMPLE 6.

With reference to the form according to fig. 6 is introduced

a feed (line 1) consisting of a gasoline with the following composition;

This feed is supplied to the liquid-liquid extraction column

(14) with 60 plates, with a flow rate of 5 kg/hour.

Through line 13, 13 kg/hour of a mixture of N-methyl-morpholin-3-one and water in the weight ratio 95/5 are sent, the entire column being kept at 40 to 45°C (peak pressure approximately 2 atmospheres absolute.

From the top of the column (line 3) a stream is taken out which mainly consists of the saturated compounds that were present in the original supply.

The extract that comes out from the bottom is supplied to the top of the column (15) top pressure approximately 1.2 atmospheres absolute).

Number of plates « 30.

The peak pressure in column 15 (line 5) is relieved by condensation in two subsequent stages at (17) and (18). Stream (6) which condenses above 120°C is mixed back into the feed while stream (7) is recycled to the bottom of the liquid-liquid extractor. The stream taken from the bottom of the column (15) (line 8) is sent to the column (16) (top pressure take 1.2 atmospheres absolute, 30 plates).

From the top, a current is taken out which is phase separated at (9).

From line 10, a flow of approximately 3.05 kg/hour of aromatic components with a specific content of saturated compounds is withdrawn, while from the bottom of the phase separator, an aqueous flow is withdrawn which is partially sent in reflux to the same column (16 (1.5 kg /hour) dg is partially recycled to column 14 (0.7 kg/hour ).The solvent withdrawn from the bottom of (10) is reused in the same liquid-liquid extractor.

EXAMPLE 7.

With reference to the schematic representation in fig. 7, a supply (line 1) consisting of a reformed petrol with the following composition is used:

This feed is sent to a first liquid-liquid extraction column (12) with 40 plates, at a flow rate of

100 kg/hour. About 250 kg/hour of N-methyl-morpholin-3-one is sent through line (5), while 40 kg/hour of pentane is sent through line (10) to the same column, keeping the extractor

.at'25°C (top<*>ppressure » 3 atmospheres absolute).

The stream taken from the top (line 2) is sent to the distillation column (13), while from its top (line 8) the pentane required for the operation of the extractor is recovered, from the bottom (line 9) a stream of approximately 61.3 kg is taken /hour composed mainly of the saturated hydrocarbons contained in the original feed (l)„

The bottom stream from the extractor (12) is sent to the second liquid-liquid extractor (14) along with about 220 kg/hr of pentane (line 11). This column consists of 20 plates and is operated constantly at 25°C and 2.0 atmospheres absolute.

The stream taken from the top (line 4) is sent to the distillation column (15), while from the top of this (line 6) the pentane necessary to drive the extractor is recovered, from the bottom (line 7) a stream of about 38.7 kg/hour of one. mixture of benzene, toluene and xylene at a specified percentage of saturated compounds.

The solvent used in step 12 is recovered from the bottom of the second extractor.

EXAMPLE 8.

With reference to the schematic representation in fig. 8,

the liquid-liquid extraction column (12) is supplied with a flow corresponding to that referred to in example 1. The same column (which consists of 50 plates and which operates at a pressure of

1.2 atmospheres absolute) is supplied through line 7 as well

150 kg/hour of a mixture composed of N-methyl-morpholin-3-one and water in the weight ratio 95/5.

From the top (wire 2) a current is taken out as after stripping

of the solvent content therein (an operation not shown in the drawing) is composed of :

30 plates).

From the top (line 4) a stream of olefins and

isoprene, which is recycled to the extractor, while a stream (5) is withdrawn from the bottom and fed to the second stripping column (14)

(peak pressure of about 1.2 atmospheres absolute, 20 plates,

L/D a 0.2).

Isoprene with a specific content is recovered from line 6

of olefins and saturated compounds, which are sent to the extractive distillation column (11) to remove the polar hydrocarbons, while the solvent necessary for the operation of the column (12) is recovered from the line (7).

The column (12) is operated under the following conditions:

From the top (line 8) a stream of very pure isoprene is taken out, which is more specifically composed of:

While the most polar hydrocarbons (1,3-cyclopentadiene and isopropyl-acetylene) are taken out in a side stream in the vapor phase (line 9), the solvent is taken out from the bottom (line 10) which is free of hydrocarbons and thus suitable for renewed use in the same column to.

EXAMPLE 9.

With reference to the form in fig. 5, gas-liquid scrubbing column (9) is supplied with a flow consisting of:

The working conditions are as follows:

The same column is fed through line 2, 1,200 kg/hour of a mixture consisting of N-methyl-morpholin-3-one and water in the weight ratio 93/7.

The bottom streams (line 4) are sent to the first stripping column (10), while a gas stream composed of:

A gas stream of olefins and saturated C. is withdrawn from the top and recirculated to the column (9), while a stream (6) is withdrawn from the bottom and fed to the second stripping column (11).

The last column is operated under the following conditions:

The gas flow is sent to the compressor (12). From the line (8), after condensation, a current is taken out which is composed of:

Part of the above-mentioned current sent to the compressor is recycled through line 7 to the column (10).

The solvent is recovered from the bottom (11) and used again in the column (9).

Claims (1)

Process for the separation of olefins, diolefins or aromatic hydrocarbons from mixtures by extraction or extractive distillation using a keto group-containing morpholine derivative, characterized in that N-methyl-morpholin-3-one is used as such solvent, possibly in a mixture with up to 20% by weight of water and /or other organic solvents.